Safety of furosemide administration in an elderly woman recovered from thiazide-induced hyponatremia
Received 21 October 2007; received in revised form 20 March 2008; accepted 25 April 2008. published online 19 June 2008.
Abstract
Background
Elderly women are at risk to develop severe hyponatremia after thiazide but not loop diuretic administration. In patients with previous thiazide-induced hyponatremia, the risk for recurrent hyponatremia after furosemide has not been established.
Methods
In order to determine how both diuretics affect water metabolism, we here compare the effects of a rechallenge with either amiloride-hydrochlorothiazide fixed association (AmHTZ; amiloride chlorhydrate 5 mg+hydrochlorothiazide 50 mg; Moduretic™) or furosemide (F; 40 mg; Lasix™) on water excretion in a 79 year old woman who was previously admitted for severe symptomatic hyponatremia secondary to a 5 days course of AmHTZ for systolic hypertension. After correction of initial hydromineral disturbances, a standard oral water load (WL; 20 mL per kg body weight) was administered before, during and after AmHTZ or F challenges.
Results
Hyponatremia developed after AmHTZ but not after F challenge. A negative free water clearance (CH2O) was only observed during AmHTZ (−0.39 mL/min), while maximal CH2O during F was 3.17 mL/min. Based on the results obtained during WL, the calculated maximal daily electrolyte free water clearance ability was only 888 mL after AmHTZ but 10,166 mL after F therapy. Taking into account a measured mean daily water intake of 1830 mL, severe hyponatremia could be predicted to occur after a few days treatment with AmHTZ. In comparison, F appears to be safer, without risk of hyponatremia, during an equivalent period of time.
Conclusions
We here showed that F may be administered to a patient with previous AmHTZ induced hyponatremia without risk for recurrent hyponatremia.
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